I went around the lake in April with camera gear and camel pack https://www.youtube.com/watch?v=SCknAyJ37oM (warning: low quality) in just over 3 hours so figured I could knock some time off. Start/finish Lake Geneva Beach. Wanted to start at 5:30 but storm clouds kept it dark until 6am. Light rain for the first couple miles then again around 9mi. No people on the trail for the first hour. The west side of the lake is quite a bit more runnable so I saved that for the second half - still enough flagstone to slow a guy down. Ran solo with a 12oz handheld. Super humid. Power hiked a short section of road around mile 18 but otherwise all runnable.
Editor's note: this FKT was preceded by one with a faster time, but this one was submitted first. By FKT policy, it will remain in the list as it was the fastest known time when submitted.